1. Field of the Invention
The invention relates to an equilibrium breaking type load carrying means for use in a treadmill and, in particular, to an equilibrium breaking type load carrying means that uses motion generating devices to produce a regular up and down motion by which the equilibrium of forces between a running belt and board of a treadmill are broken, resulting in a reduction in friction forces between the running belt and board of the treadmill and an enhancement of a treadmill's performance.
2. Description of a Prior Art
Along with advances in social economies and scientific technologies, it has become popular for people to use treadmills for physical training or maintaining physical strength. However, the prior art treadmills have many drawbacks in design and production.
A prior art treadmill together with its load carrying means is shown in FIGS. 1 and 2. This treadmill has a running board 02 that sits on a receiving surface 03 of supporting rails 05 of a bear frame and is fastened by screws 01 to the supporting rails 05. By means of the relative motion between the running board 02 and belt 04, the treadmill functions to simulate running thereon by users for exercising purposes. However, such a design contains drawbacks as discussed below.
The present inventor tested treadmills available in the U.S. market. One such treadmill is a T-brand (TUNTURI) treadmill. This treadmill uses an AC 110 V power source and has a maximum load capacity of ninety kilograms and a maximum speed of ten miles per hour with an accuracy of plus or minus 0.5 miles per hour. Its motor output power is 1.75 hp, and it adopts T1 brand running boards and T2 brand running belts with a service life of 300 hours. The T1 brand running board combined with the T2 brand running belt is an excellent match, hardly substituted by other brand products. For instance, when in a low speed range (below 6 miles per hour), products of a first experimental group of conventional treadmills each consumed two to four more amperes in comparison with those of a second experimental group operated at varied speeds. The products of the second experimental group are T-brand treadmills and were tested under an eighty-five kilogram load and at a variety of speeds. In the second experimental group the consumed current load increased approximately linearly from six amperes to twelve amperes as the treadmill's speed increased from 0.6 to 10 miles per hour. In the gust experimental group, the consumed current load can reach a highest value of ten amperes for some products at a speed of six miles per hour. At that time, other functions of the treadmills work normally except for these unfavorable overcurrents. However, when treadmills of the second experimental group (TUNTURI brand) take an external load of eighty-five kilograms and run at ten miles per hour, the consumed current load is twelve amperes. If the running board (of T1 brand) or belt (of T2 brand) is replaced by other brand parts, the consumed current loads in all the experimental products under the same conditions was over twelve amperes. Some of these products cannot reach ten miles per hour, because the friction between running boards and belts is too large and the current load exceeds fifteen amperes, so that the automatic circuit breakers contained therein are actuated. On the average maximum household electricity capacity is fifteen amperes at 110 volts, thus the consumed current load of a treadmill must be below this value. For such reasons, the maximum speed of a conventional treadmill is restricted by the current capacity. This is a most significant drawback of a conventional treadmill.
Running boards used in a conventional treadmill cannot maintain a low friction condition for a long time. Perhaps about 30 hours is the maximum time. The low friction condition is important to reduce powder consumption due to friction between running boards and running belts or to provide a larger effective output power for the treadmill. In a prior art treadmill, the consumed electric current grows when the running board approaches the end of its service life, because the friction between the running board and belt increases at this time. This is another drawback of a conventional treadmill. As the ratio of power consumption for overcoming friction to motor output power decreases, the maximum speed and the load capacity of a treadmill increases.
In view of the above-mentioned drawbacks of a prior art treadmill, it would be advantageous provide a load carrying means having less friction.